Knoxville, TN – Officials say the Tennessee Valley Authority is selling more "green power" than it's actually producing. But TVA says 15 wind turbines being erected on a former strip mine near Knoxville could turn that deficit into a huge surplus that would make renewable energy available to more consumers. The renewable energy program is the largest in the Southeast. It charges customers more for green power on the promise that it produces a like amount of electricity from renewable sources like wind power. But without the windmills, the national accreditation of TVA's Green Power Switch program hangs in the balance.